1. Field
The present application relates generally to optical sensors, and more specifically to fiber optic sensors.
2. Description of the Related Art
Recently, a great deal of attention has been focused on greatly reducing the group velocity of light to be significantly less than the speed of light in vacuum (referred to as “slow light”). Systems such as electronically induced transparency (see, e.g., S. E. Harris, “Electromagnetically induced transparency,” Phys. Today, Vol. 50, No. 7, 36-42 (1997)), Bragg fibers (see, e.g., C. Lin, W. Zhang, Y. Huang, and J. Peng, “Zero dispersion slow light with low leakage loss in defect Bragg fiber,” Appl. Phys. Lett., Vol. 90, 031109 (2007)), and coupled resonator arrays (see, e.g., A. Yariv, Y. Xu, R. K. Lee and A. Scherer, “Coupled resonator optical waveguide: a proposal and analysis,” Opt. Lett., Vol. 24, No. 11, 711-713 (1997)) have all been shown to reduce the group velocity of light by orders of magnitude. Each of these references is incorporated in its entirety by reference herein. In addition, slow light has been studied in photonic-bandgap structures. (See, e.g., M. Soljacic, S. G. Johnson, S. Fan, M. Ibansecu, E. Ippen and J. D. Joannopoulos, “Photonic-crystal slow-light enhancement of nonlinear phase sensitivity,” J. Opt. Soc. Am. B, Vol. 19, No. 9, 2052-2059 (2002); U.S. Pat. No. 6,917,431, “Mach-Zehnder interferometer using photonic band gap crystals,” issued on Jul. 12, 2005; U.S. Pat. No. 7,116,864, “Stopping and time reversing light in a waveguide with an all-optical system,” issued on Oct. 3, 2006; M. F. Yanik and S. Fan, “Stopping light all-optically,” Phys. Rev. Lett., Vol. 92, 083901 (2004); M. F. Yanik, W. Suh, Z. Wang, and S. Fan, “Stopping light in a waveguide with an all-optical analogue of electromagnetic induced transparency,” Phys. Rev. Lett., Vol. 93, 233903 (2004); M. F. Yanik and S. Fan, “Stopping and storing light coherently,” Phys. Rev. A, Vol. 71, 013803 (2005); S. Sandhu, M. L. Povinelli, M. F. Yanik, and S. Fan, “Dynamically-tuned coupled resonator delay lines can be nearly dispersion free,” Optics Lett., Vol. 31, 1985-1987 (2006), each of which incorporated in its entirety by reference herein).